Recent enhancement and diversification of information apparatus such as computers are indeed remarkable. As the capacity of such a storage as an HDD (hard disc drive) used for each of such computers is expanded more and more, the user of the computer usually stores his/her information in the computer. On the other hand, computers installed in offices are now placed under possibility of illegitimate and/or illegal accesses from uncertified users. This has lead to a problem that the information stored in the computer is sometimes read and rewritten by uncertified users.
In order to prevent a computer from such illegitimate and/or illegal uses, therefore, there is a well-known method that uses passwords. A password for a certified user is set in the subject computer beforehand, so that the computer is started up only when the password entered at the time of powering the computer is identical to a preset stored password.